Cheapest priced copy (Foundations): $0.35 at Card Kingdom, near mint, their price list as of .
Mocking Sprite 
Creature — Faerie Rogue · 2/1 · Common · Foundations · #744
Flying
Instant and sorcery spells you cast cost {1} less to cast.
Legal inCommanderBrawlStandardPioneerModernLegacyVintagePauper
3 printings · $0.35 to $0.49 at Card Kingdom
| Set | Number | Rarity | Card Kingdom | Foil |
|---|---|---|---|---|
| Foundations | 159 | Common | $0.35 | $0.49 |
| Foundations | 744 | Common | — | — |
| Wilds of Eldraine | 62 | Common | $0.35 | $0.49 |
2 rulings from Wizards of the Coast
- 1 September 2023Mocking Sprite's last ability can't reduce the amount of colored mana you pay for a spell. It reduces only the generic mana component of that cost.
- 1 September 2023Mocking Sprite's last ability doesn't change the mana cost or mana value of any spell. It changes only the total cost you pay.